I recently acquired an older model of PC, and the network card in it did not work. A friend of mine had a spare laying around for me to use as a replacement, but I noticed that it only had 4 of the 8 pins to connect to the cable. He said this wasn't a problem and that it would work, but couldn't explain why (the non-functional one that came with the PC had all 8). I tested it out, and sure enough, it works. How can it work if it only has 4 of the 8 connectors?
Conductors required 10BASE-T and 100BASE-TX Ethernet connections require two cable pairs. 1000BASE-T Ethernet connections require four cable pairs.
Does it matter which two cable pairs are present? Or can any two pairs be used?